{"id":26786,"date":"2026-07-19T17:39:11","date_gmt":"2026-07-19T16:39:11","guid":{"rendered":"https:\/\/www.cathive.co.uk\/advice\/fitting-a-catalytic-converter\/"},"modified":"2026-10-01T19:33:51","modified_gmt":"2026-10-01T18:33:51","slug":"fitting-a-catalytic-converter","status":"publish","type":"page","link":"https:\/\/www.cathive.co.uk\/nl\/advice\/fitting-a-catalytic-converter\/","title":{"rendered":"Een katalysator monteren, stap voor stap"},"content":{"rendered":"<p>This is a practical, step-by-step guide to replacing a catalytic converter, based on the manufacturer&#8217;s own fitting guidance. It assumes competent DIY skills or a professional workshop \u2014 exhaust work involves a raised vehicle, seized fasteners and (until it cools) serious heat. If any step is outside your comfort zone, have a garage do the job; poor fitting is a leading cause of early failure and can invalidate the warranty.<\/p>\n<p><strong>Before anything else:<\/strong> make sure you know <a href=\"\/advice\/why-catalytic-converters-fail\/\">why the old cat failed<\/a> and that the cause has been fixed. And note the new unit&#8217;s serial number (six letters, pin-stamped on the body) before it goes on the car \u2014 you&#8217;ll need it for any warranty query and it can be unreadable once fitted.<\/p>\n<h2>Preparation<\/h2>\n<ul>\n<li>Let the exhaust cool completely \u2014 catalytic converters run at several hundred degrees and hold heat for a long time.<\/li>\n<li>Disconnect the battery earth terminal, so removing lambda sensors can&#8217;t upset the ECU.<\/li>\n<li>Raise the vehicle on a ramp \u2014 never work under a car supported only on jacks, and fit the catalyst with the vehicle on a ramp rather than axle stands.<\/li>\n<li>Offer the new part up against the old one before you start: same flanges, same bends, same sensor positions. <strong>If it looks like it would need modifying to fit, stop<\/strong> \u2014 you almost certainly have the wrong part for the vehicle, and any alteration voids the warranty. <a href=\"mailto:info@cathive.co.uk\">Email us<\/a> and we&#8217;ll check the fitment.<\/li>\n<li>Soak all nuts, bolts and clamps in penetrating oil \u2014 ideally the day before.<\/li>\n<\/ul>\n<h2>Removal<\/h2>\n<ol>\n<li>Photograph the installed unit from a couple of angles \u2014 a reference for routing and orientation later.<\/li>\n<li>Identify any lambda\/oxygen sensors on the old unit. Unplug their connectors, then unscrew the sensors carefully \u2014 they seize readily and are easily damaged. Keep them somewhere protected.<\/li>\n<li>Loosen all retaining nuts, bolts and clamps. Seized fittings may need more penetrating oil or careful heat (with appropriate precautions).<\/li>\n<li>Support the rest of the exhaust so nothing hangs on the manifold, then remove the old unit \u2014 get a second pair of hands if it&#8217;s large or heavy.<\/li>\n<\/ol>\n<h2>Fitting<\/h2>\n<ol>\n<li>Clean all mating surfaces back to sound metal and remove old gasket residue \u2014 air leaks at the joints ahead of a cat cause false lambda readings, MOT failures and premature cat death.<\/li>\n<li>Use a new <a href=\"\/product-category\/fitting-kit\/\">fitting kit<\/a> wherever possible: new gaskets, clamps, nuts and bolts. Old fixings lose thread and length to corrosion.<\/li>\n<li><strong>Never use exhaust assembly paste on any joint before the cat.<\/strong> Hardened paste breaks up and destroys the monolith from the inside \u2014 and it&#8217;s an automatic warranty exclusion. If a sealant is genuinely needed, use a silicone-based one.<\/li>\n<li>Hang the new unit loosely \u2014 all fixings started but nothing tight \u2014 and align it with the rest of the system.<\/li>\n<li><strong>Never strike the unit<\/strong> with a hammer or mallet to persuade it into position; the ceramic core will fracture.<\/li>\n<li>Refit the lambda sensors to the manufacturer&#8217;s torque \u2014 snug, not brutal \u2014 and reconnect their wiring, keeping cables clear of hot surfaces.<\/li>\n<li>Check clearance all round: the unit must not touch the floor pan, heat shields or anything else once the engine rocks under load.<\/li>\n<li>Tighten everything fully, working from the manifold back. Take care not to over-tighten.<\/li>\n<\/ol>\n<h2>After fitting<\/h2>\n<ul>\n<li>Reconnect the battery, start the engine and check every joint for leaks \u2014 listen, and feel by hand around (not on) the joints. Re-lift the vehicle if needed.<\/li>\n<li>Clear any stored fault codes so the ECU starts fresh.<\/li>\n<li>Avoid hard driving for the first few miles while everything beds in, then re-check the fixings after a heat cycle if you can.<\/li>\n<\/ul>\n<p>Need the right part first? Use the <a href=\"\/#ch-make\">part finder<\/a> or browse <a href=\"\/product-category\/catalytic-converter\/\">catalytic converters<\/a>. Fitting a DPF instead? That job has extra, non-optional steps \u2014 see <a href=\"\/advice\/fitting-a-dpf\/\">fitting a DPF<\/a>.<\/p>\n<p><strong>Find the part:<\/strong> browse <a href=\"\/product-category\/catalytic-converter\/\">catalytic converters<\/a>, <a href=\"\/product-category\/exhaust-pipe\/\">front and connecting pipes<\/a> and <a href=\"\/product-category\/fitting-kit\/\">fitting kits<\/a>, or go straight to your vehicle: <a href=\"\/parts\/ford\/focus\/\">Ford Focus catalytic converters<\/a>, <a href=\"\/parts\/volkswagen\/golf\/\">Volkswagen Golf catalytic converters<\/a> or <a href=\"\/parts\/\">all vehicles<\/a>.<\/p>\n<p><a href=\"\/advice\/\">&larr; Back to Help &amp; Advice<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Een katalysator vervangen: voorbereiding, demontage, montage en controle, plus de fouten die tot vroegtijdige uitval leiden of de garantie kosten.<\/p>\n","protected":false},"author":0,"featured_media":0,"parent":26778,"menu_order":80,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-26786","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26786","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/types\/page"}],"replies":[{"embeddable":true,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/comments?post=26786"}],"version-history":[{"count":1,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26786\/revisions"}],"predecessor-version":[{"id":26927,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26786\/revisions\/26927"}],"up":[{"embeddable":true,"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/pages\/26778"}],"wp:attachment":[{"href":"https:\/\/www.cathive.co.uk\/nl\/wp-json\/wp\/v2\/media?parent=26786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}